When comparing Judy Arrays vs UTHash, the Slant community recommends UTHash for most people. In the question“What are the best open-source map/hash-table libraries for C?” UTHash is ranked 1st while Judy Arrays is ranked 2nd. The most important reason people chose UTHash is:
UTHash is released under the BSD license, which allows its redistribution even for commercial use.
Ranked in these QuestionsQuestion Ranking
Pros
Pro Memory efficient
Pro Very cache-friendly when accessing things in order
Judy is pretty good at inserting and looking up keys in order. This makes Judy probably unbeatably the best when it comes to being cache-friendly.
Pro BSD license
UTHash is released under the BSD license, which allows its redistribution even for commercial use.
Pro Well documented
UTHash documentation is detailed, well organized and uses plenty of examples.
Pro Easy to use
UTHash is straight forward to use and is easy to install.
Cons
Con Slow for random access and sparse keys
Con Not the fastest/slimmest option
There are other options which either show better performance characteristics or better memory usage (as in overhead per item), or sometimes both. Specific comparison micro benchmarks including plots for the data can be found here.